Sheet metal snap fastener



July 10, 1951 H. T. BuRDlck 2560,530

sHEE'r METAL sNAP FASTENER v Filegi Sept. 25, 1947 Patented July 10,1951 SHEET METAL SNAP FASTENER Hugh T. Burdick, Chicago, Ill., assignorto Illinois Tool Works, Chicago, Ill., a, corporation of IllinoisApplication September 25, 1947, Serial No. 776,107

2 Claims. 1

This invention relates generally to fastening devices and moreparticularly to fastening devices formed from sheet metal stock adaptedto be snapped into position within the aperture` of a work piece.

More specifically, the present invention is concerned with theproduction of a fastening device of the tubular shank variety adaptedfor telescopic association with a Work aperture and which isself-looking within the work piece upon reaching its final position ofinsertion. Fastening devices of the aforesaid type present certainproblems in use which the present invention proposes to obviate. Forexample, tubular shanks made of sheet metal, and particularly thosecomprising two semi-cylindrical portions brought together in edge toedge abutting relation, have a tendency to become misaligned. That is tosay, one semi-cylindrical half may become laterally displaced withrespect to the other half, thereby seriously aifecting the functionalefiiciency of the device.) The present invention contemplates afastening device in which a tu-bular shank or body portion is so formedthat abutting margins of semi-oylindrical halves will always remain infirm, aligned, abutting relation.

It is not uncommon for fastening devices of the type referred to aboveto employ struckout wings or fingers which enable the fastener to beselfpositioning or looking when finally driven home within a workaperture. As the shank portion moves through the aperture these Wings orfingers are forced back into the openings from which they were struck,and as the fastener reaches the limit of its position of insertion thefingers are supposed to automatically spring outwardly into lookingposition. Not infrequently, when the fingers are forced inwardly asabove stated, the sheared edges become interlocked with thecomplementary sheared edges of the tubular shank and hence the fingerswill not spring outwardly into looking position as the fastener isdriven home. It is an important object of the present invention to forma sheet metal fastening device in which binding or interlocking of thelooking fingers as they are forced back into the confines of the tubularshank is positively precluded. To this end the fastener shank is soformed as to obviate the necessity of shearing wings or fingers from thebody of the tubular shank.

It is a further object of the present invention to provide a fastener asset forth above in which the shank wall has a novel structuralconfiguration which not only assures aligned abutting relation ofcomplementary shank halves, but ma- 2 terially ncreases the transverseshear strength and longitudinal strength of the shank body.

It is a further object of the present invention to provide a sheet metalsnap-in fastening device in .which the shank portion provides acontinuous; or completely sealed peripheral carea, thereby rendering thedevice particularly practical for use in instances where it is importantto employ a fastener which will completely fill and seal a workaperture.

Still more specifically, it is anV object of the present invention toprovide a fastener having the advantages of shank construction referred'to above, in association with a head at one ex-f tremity which isresilient and thereby cooperates: with a looking protuberance on theshank firmly to secure the fastener in place after being driven orforced into the work aperture.

The foregoing and other objects and advantages will be more apparentfrom the following; detailed description when considered in connectionwith the accompanying drawing, wherein:

Figure 1 is a plan view of the fastener appliedl to a work piece;

Figure 2 is a view of the underside of the fastener as shown in Figure1;

Figure 3 is an enlarged end view of the fas-- tener shown in Figure 1;

Figure 4 is a side view of the fastener as vieweil from the right ofFigure 3;

Figure 5 is a sectional view of thev fastener taken along the line 5-5of Figure 1 and showing the fastener before complete insertion intoJ thework aperture of a work piece;

Figure 6 is a sectional view similar to Figure 5 showing the fastener inoperative position relative to the work piece;

Fgure 7 is a perspective view of the fastener' with a portion of theshank broken away in order' more clearly to illustrate structuralcharacteristics of the tubular shank;

lFigure 8 is a cross sectional view of the fastener shank taken alongthe line 8-8 of Figure 4;

Figure 9 is a cross sectional view of the fastener shank taken along theline 9-9 of Figure 4; Figure 10 is aplan view of the blank from whichthe fastener shown in Figures 1 to 9 is i formed; and

Figure 11 isra perspective view of a modified embodiment of the fastenerwith a portion of the shank broken away.

The fastener 23 of the present invention is comprised of a strip ofmetal 22 bent adjacent its midportion to form a nose portion 24. Con

'caved complementary body portions 26 and 28 extend from the noseportion 24, the material of strip 22 being bent outwardly adjacent theextremity of the free end of the strip to form head portions 39 and 32.The head portions 30 and 32 disclosed in Figures 1 to 9 are resilientand when fiexed serve to exert axial tightening force as shown in Figure6.

The body portions 25 and 28 are provided with inturned longitudinalflanges St, 35, 38 and 40 which extend a desired distance along thelongitudinal axis of the shank body. These longltudinal fianges 3d and38, and 36 and 40, respectively, are designed to lie in abuttingrelation when the concaved complementary body portions 26 and 28 aredrawn together to form the shank of the fastener 2%. These longitudinalflanges increase the abutting area of the shank portions 26 and 28 andhelp to prevent collapse of the shank when it is subjected to transverseshear stresses. These flange portions 26 and 28 can be made to extendvarious lengths along the fastener shank depending on the use of thefastener in each particular application. In the embodiment shown inFigures l to 10, the longitudinal flange portions li 38 and (w extendonly a portion ofthe length of the shank, although it should be noted inFigure 1.1. that these flanges extend substantiall'y the entire lengthof the shank body. This feature of construction in the embodiment shownin Figure 11 will be described in more detail later.

I have provided the fastener 2G With resilient wings or fingers ll and44 extending from the nose portion 2-4 toward the head portions 30-32.These resilient fingers or protuberances 4'2 and 44 have their freeendsin opposed relation to head portions 3G and- 3-2'and are adapted toengage the wall of the work piece Q6 opposite from said head portionswhen the fastener shank has been inserted completely into the workaperture. These wings 42 and ll are adapted to overlie the materialformi-ng the shank of the fastener, as illustrated in Figure 8. In thisconnection it will 'ee notedV that the material of the' shank isdepressed to provide recesses 59 and 52, the materia-l in that vicinitybeing positioned immediately beneath the resilient wings 42 and M topermit them' in collapsed position to lie within the diameter of theperiphery of the shank formed" by the body portions and` 28:. Such anarrangement perm'its ready collapse of the resilient wings 42 and mi inassociation with an un'- broken or continuous shank whichaddsmaterial'ly to the shear' strength. Furthermore, such design provides ashank pi'esenting a substantially unbroken cup foi` better sealing thework' aperture into which the fastener 20 is inserted. The combinationof the recesses E and' 52 of the shanl and resiiient Wing portions li?and 4'4' is best seen in Figure 5 wherein' the wings' are shownincoll'apsed position and seated within the recesses 5G and 52. InFigure 6 the' wings 42 and 1M are shown after having passed through theWork aperturek and' expanded from the' recessed portions 5G' and 52,respectively, into interlocking engagernent with the work surfaceoppo'si'tely disposed from the head.

GTI

In Figure 10 I have shown the blank 22 of the' fastener disclosedinFigs'. 1 to 9. Various portions havebeen' numbered to correspond withthe numerals used in Figs. 1 to 9.

It willi be seenV that the blank' 22'` may be stamped from fiat stock bytheV use' of Conventional stamping methods, and said bl'anl` subsc- 4quently may be formed into the complete structure shown in the drawing.It will also be apparent from the foregoing description that theaforesaid blank enables a fastener to be produced therefrom in which atubular shank portion is completely sealed along its periphery and atits entering extremity. Furthermore, the inturned nanges 34-38 and 36 iextending in abutting relation over a substantial axial extent of theshank make for transverse and longitudinal rigidity. By having 'theaforesaid flanged abutment's absolute uniformity in axial alignment ofthe shank halves is assured. Also, by having the material of the shankextend beneath each of the wings or fingers 42-34, as clearly shown inFig. 8, this area is sealed. Furthermore, by employing the depressions58-52, as distinguished from conventional struck out por tions whichhave heretofore been used, the ngers [i-'44 cannot possibly becomeinterlocked with the shank stock as they are forced inwardly to thepositions shown in 5 during the initial insertion of the fastener withinthe work aperture.

In Pig. 11 I have disclosed another embodiment of the present invention,incorporating in a slightly different manner the features heretoforedescribed. The fastener is designated generally by the numeral a andincludes a nose portion 25a, concaved body portions 23a and 28a, andrigid head portions and 32a. Rigid head p'ortions are preferable wherethe fastener' is' not designed to acoonimodate various' thicknes's'es ofmaterial. Recessed portions 58a and 52a are provided so that the wings62a and Ma may be cole lapsed therein upon insertion of the fastenerinto a work piece. Inwardly extending flanges 34a, 36a, a and tea areprovided along the longitudinal edges of the body portions 26a and 28afor purposes heretofore disolosed. It should be noted that thesevportions in this embodiment extend substantially for the entire lengthof the shank of the body to provide maximum strength to thev body so as'to prevent collapse of the shank portion when transverse shear stressesare present.

It will be apparent from the foregoing description that the fastener23a, lile the fastener 20, is so formed as to prevent the Wings orresilient fingers l2 -''a from becoming interlocke'd or wedged withinthe fastener shank. By having the inturned fianges extend substantiallythe length of the fastener, as illustrated inFig. 11', maximumtransverse and longitudinal shank strength is assured. Also, the closedend and. continuous abutting relationship of the adjacent longitudinalmargins of the shankstock provide an effective sealed. constructionVVsimilar to that shown in Figs. l to 9, inclusive.

While certain features of construction have been described. herein forthe purpose of i'llustrating practical embodimentsV of the inventiom it`will be apparent that other modificationsand? changesmay be made withoutdeparting from the scope of the appended. claims;

The invention is hereby claimed as fol'lowsiz- I. Alv Sheet metalfastener including a t'ubula'r` shank forme-d of a' pair of oppositelyconcaved` el'ongat'ed. sheet metal shank Sections joined* at theirentering ends' by an imperforate' noseA portion and adapted to abutalong theircomplementary l'ongitudinaly margins, a head portion'extending laterall'y from saidV shank at the opposit'e end thereof forengaging one side of a work structure, resilient' latching membersformedinteg'r'al with and' extending from said connecting nose portiontoward said head and normaliy projecting beyond the periphery of thetubular shank for engaging the side of a work structure oppositelydisposed from the fastener head but capable of being fiexed nwardly Whentelescopically associated With a Work aperture, and a portion of theperiphery of said tubular shank inwardly indented a suificient amount topermit a oomplementary latching member to be forced into alignment withthe shank periphery during the passage of said shank through a workaperture, the material of the shank defining said indentaton closing thearea of the shank underiying said latching member and including portionsof said abutting shank margins.

2. A sheet metal fastener in accordance with claim 1, Wherein at leastportions of the abutting margins of the elongated shank members consistof radiaily extending flanges which assure abutting alignment andincreased shank strength.

HUGH T. BURDICK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STA'I'ES PATENTS Number Name Date 1,131,085 Reiily Mar. 9, 19151,303,-502 Rundell May 13, 1919 2,244,975 Tinnerman June 10, 19412,391,298 Davis Dec. 18, 1945 2,408,340 Poupitch Sept. 24, 19462,430,809 Flora Nov. 11, 1947

